As cancer is one of the leading causes of death in the United States with some sub-types remaining essentially untreatable, expansion of available drug targets will provide significant new options for the development of more effective antineoplastic agents. The major goal of this project is to apply a unique drug discovery strategy to cancer drug development. This will be accomplished through application of this methodology to the discovery and characterization of new drug-like small molecule therapeutics disrupting interactions relevant to anti-cancer therapy. Improved strategies for developing pharmaceuticals based on inhibitors of protein-protein interactions would be beneficial in order to overcome the limitations of the majority of currently druggable targets to those involving ligand-receptor and enzyme-substrate interactions. We will focus our efforts on the Cyclin Dependent Kinase substrate recruitment site as a validated antitumor drug target. Through this site, the opportunity exists to develop potent and selective inhibitors that are specific to the cell cycle CDKs. Such compounds possessing appropriate drug-like characteristics will potentially be different mechanistically from ATP competitive CDK inhibitors, targeting tumor cells selectively and thereby addressing issues with agents currently being developed.